The present invention is directed to digital communications and, particularly, to connectors for providing serial communications between digital devices.
When providing serial connections between digital devices ("DDs"), it is sometimes appropriate to connect the transmit ("Tx") pin of one DD to the receive ("Rc") pin the other DD and to connect the receive Rc pin of the first DD to the Tx pin of the other DD. This is called a "null modem pin-through" and is typically required, for example, when coupling two computers to one another.
In other instances, it is necessary to connect the Tx pin of the first DD to the Tx pin of the other DD and to connect the Rc pin of the first DD to the Rc pin of the modem. This is typically called a "straight pin-through" and is typically required when one of the DDs is a modem or other such communications device.
Most DDs are provided with an industry-standard serial port, the most common of which is the RS-232 port. This is a 9-pin connector adapted to receive a matching plug. To avoid confusion, the RS-232 port (and other industry standard ports) have a definite "sense," meaning that they mate with corresponding plugs only when the plug and port are oriented in the same direction.
This can be highly convenient, e.g., when connecting a modem to a computer using a standard "serial cable"--that is, a cable with RS-232 plugs wired such that the respective Tx pins are directly connected with one another and, likewise, such that the respective Rc pins of the plugs are directly connected with one another.
However, it can be highly inconvenient when attempting to connect two computers to one another. In this instance, a special adaptor--referred to as a null-modem adaptor--must be utilized effectively to reverse the Tx and Rc pins of one of the DDs. Alternatively, a special cable must be wired, called a null-modem cable, in which the wires connecting the Tx and Rc pins are crossed.
In view of the foregoing, there exists a need for a serial connector which is capable of attaching all types of DDs to one another, regardless of whether the Tx and Rc pins on one DD are to be directly connected to the Tx and Rc pins, respectively, on another DD; or whether the Tx and Rc pin connections are to be reversed.